/**
 * @license
 * Copyright 2015 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * Class constructor for dropdown MDL component.
 * Implements MDL component design pattern defined at:
 * https://github.com/jasonmayes/mdl-component-design-pattern
 * @param {HTMLElement} element The element that will be upgraded.
 */
function MaterialMenu(element) {
  'use strict';

  this.element_ = element;

  // Initialize instance.
  this.init();
}

/**
 * Store constants in one place so they can be updated easily.
 * @enum {string | number}
 * @private
 */
MaterialMenu.prototype.Constant_ = {
  // Total duration of the menu animation.
  TRANSITION_DURATION_SECONDS: 0.3,
  // The fraction of the total duration we want to use for menu item animations.
  TRANSITION_DURATION_FRACTION: 0.8,
  // How long the menu stays open after choosing an option (so the user can see
  // the ripple).
  CLOSE_TIMEOUT: 150
};

/**
 * Keycodes, for code readability.
 * @enum {number}
 * @private
 */
MaterialMenu.prototype.Keycodes_ = {
  ENTER: 13,
  ESCAPE: 27,
  SPACE: 32,
  UP_ARROW: 38,
  DOWN_ARROW: 40
};

/**
 * Store strings for class names defined by this component that are used in
 * JavaScript. This allows us to simply change it in one place should we
 * decide to modify at a later date.
 * @enum {string}
 * @private
 */
MaterialMenu.prototype.CssClasses_ = {
  CONTAINER: 'mdl-menu__container',
  OUTLINE: 'mdl-menu__outline',
  ITEM: 'mdl-menu__item',
  ITEM_RIPPLE_CONTAINER: 'mdl-menu__item-ripple-container',
  RIPPLE_EFFECT: 'mdl-js-ripple-effect',
  RIPPLE_IGNORE_EVENTS: 'mdl-js-ripple-effect--ignore-events',
  RIPPLE: 'mdl-ripple',
  // Statuses
  IS_UPGRADED: 'is-upgraded',
  IS_VISIBLE: 'is-visible',
  IS_ANIMATING: 'is-animating',
  // Alignment options
  BOTTOM_LEFT: 'mdl-menu--bottom-left',  // This is the default.
  BOTTOM_RIGHT: 'mdl-menu--bottom-right',
  TOP_LEFT: 'mdl-menu--top-left',
  TOP_RIGHT: 'mdl-menu--top-right',
  UNALIGNED: 'mdl-menu--unaligned'
};

/**
 * Initialize element.
 */
MaterialMenu.prototype.init = function() {
  'use strict';

  if (this.element_) {
    // Create container for the menu.
    var container = document.createElement('div');
    container.classList.add(this.CssClasses_.CONTAINER);
    this.element_.parentElement.insertBefore(container, this.element_);
    this.element_.parentElement.removeChild(this.element_);
    container.appendChild(this.element_);
    this.container_ = container;

    // Create outline for the menu (shadow and background).
    var outline = document.createElement('div');
    outline.classList.add(this.CssClasses_.OUTLINE);
    this.outline_ = outline;
    container.insertBefore(outline, this.element_);

    // Find the "for" element and bind events to it.
    var forElId = this.element_.getAttribute('for');
    var forEl = null;
    if (forElId) {
      forEl = document.getElementById(forElId);
      if (forEl) {
        this.forElement_ = forEl;
        forEl.addEventListener('click', this.handleForClick_.bind(this));
        forEl.addEventListener('keydown',
            this.handleForKeyboardEvent_.bind(this));
      }
    }

    var items = this.element_.querySelectorAll('.' + this.CssClasses_.ITEM);

    for (var i = 0; i < items.length; i++) {
      // Add a listener to each menu item.
      items[i].addEventListener('click', this.handleItemClick_.bind(this));
      // Add a tab index to each menu item.
      items[i].tabIndex = '-1';
      // Add a keyboard listener to each menu item.
      items[i].addEventListener('keydown',
          this.handleItemKeyboardEvent_.bind(this));
    }

    // Add ripple classes to each item, if the user has enabled ripples.
    if (this.element_.classList.contains(this.CssClasses_.RIPPLE_EFFECT)) {
      this.element_.classList.add(this.CssClasses_.RIPPLE_IGNORE_EVENTS);

      for (i = 0; i < items.length; i++) {
        var item = items[i];

        var rippleContainer = document.createElement('span');
        rippleContainer.classList.add(this.CssClasses_.ITEM_RIPPLE_CONTAINER);

        var ripple = document.createElement('span');
        ripple.classList.add(this.CssClasses_.RIPPLE);
        rippleContainer.appendChild(ripple);

        item.appendChild(rippleContainer);
        item.classList.add(this.CssClasses_.RIPPLE_EFFECT);
      }
    }

    // Copy alignment classes to the container, so the outline can use them.
    if (this.element_.classList.contains(this.CssClasses_.BOTTOM_LEFT)) {
      this.outline_.classList.add(this.CssClasses_.BOTTOM_LEFT);
    }
    if (this.element_.classList.contains(this.CssClasses_.BOTTOM_RIGHT)) {
      this.outline_.classList.add(this.CssClasses_.BOTTOM_RIGHT);
    }
    if (this.element_.classList.contains(this.CssClasses_.TOP_LEFT)) {
      this.outline_.classList.add(this.CssClasses_.TOP_LEFT);
    }
    if (this.element_.classList.contains(this.CssClasses_.TOP_RIGHT)) {
      this.outline_.classList.add(this.CssClasses_.TOP_RIGHT);
    }
    if (this.element_.classList.contains(this.CssClasses_.UNALIGNED)) {
      this.outline_.classList.add(this.CssClasses_.UNALIGNED);
    }

    container.classList.add(this.CssClasses_.IS_UPGRADED);
  }
};

/**
 * Handles a click on the "for" element, by positioning the menu and then
 * toggling it.
 * @private
 */
MaterialMenu.prototype.handleForClick_ = function(evt) {
  'use strict';

  if (this.element_ && this.forElement_) {
    var rect = this.forElement_.getBoundingClientRect();
    var forRect = this.forElement_.parentElement.getBoundingClientRect();

    if (this.element_.classList.contains(this.CssClasses_.UNALIGNED)) {
      // Do not position the menu automatically. Requires the developer to
      // manually specify position.
    } else if (this.element_.classList.contains(
        this.CssClasses_.BOTTOM_RIGHT)) {
      // Position below the "for" element, aligned to its right.
      this.container_.style.right = (forRect.right - rect.right) + 'px';
      this.container_.style.top =
          this.forElement_.offsetTop + this.forElement_.offsetHeight + 'px';
    } else if (this.element_.classList.contains(this.CssClasses_.TOP_LEFT)) {
      // Position above the "for" element, aligned to its left.
      this.container_.style.left = this.forElement_.offsetLeft + 'px';
      this.container_.style.bottom = (forRect.bottom - rect.top) + 'px';
    } else if (this.element_.classList.contains(this.CssClasses_.TOP_RIGHT)) {
      // Position above the "for" element, aligned to its right.
      this.container_.style.right = (forRect.right - rect.right) + 'px';
      this.container_.style.bottom = (forRect.bottom - rect.top) + 'px';
    } else {
      // Default: position below the "for" element, aligned to its left.
      this.container_.style.left = this.forElement_.offsetLeft + 'px';
      this.container_.style.top =
          this.forElement_.offsetTop + this.forElement_.offsetHeight + 'px';
    }
  }

  this.toggle(evt);
};

/**
 * Handles a keyboard event on the "for" element.
 * @private
 */
MaterialMenu.prototype.handleForKeyboardEvent_ = function(evt) {
  'use strict';

  if (this.element_ && this.container_ && this.forElement_) {
    var items = this.element_.querySelectorAll('.' + this.CssClasses_.ITEM +
      ':not([disabled])');

    if (items && items.length > 0 &&
        this.container_.classList.contains(this.CssClasses_.IS_VISIBLE)) {
      if (evt.keyCode === this.Keycodes_.UP_ARROW) {
        evt.preventDefault();
        items[items.length - 1].focus();
      } else if (evt.keyCode === this.Keycodes_.DOWN_ARROW) {
        evt.preventDefault();
        items[0].focus();
      }
    }
  }
};

/**
 * Handles a keyboard event on an item.
 * @private
 */
MaterialMenu.prototype.handleItemKeyboardEvent_ = function(evt) {
  'use strict';

  if (this.element_ && this.container_) {
    var items = this.element_.querySelectorAll('.' + this.CssClasses_.ITEM +
      ':not([disabled])');

    if (items && items.length > 0 &&
        this.container_.classList.contains(this.CssClasses_.IS_VISIBLE)) {
      var currentIndex = Array.prototype.slice.call(items).indexOf(evt.target);

      if (evt.keyCode === this.Keycodes_.UP_ARROW) {
        evt.preventDefault();
        if (currentIndex > 0) {
          items[currentIndex - 1].focus();
        } else {
          items[items.length - 1].focus();
        }
      } else if (evt.keyCode === this.Keycodes_.DOWN_ARROW) {
        evt.preventDefault();
        if (items.length > currentIndex + 1) {
          items[currentIndex + 1].focus();
        } else {
          items[0].focus();
        }
      } else if (evt.keyCode === this.Keycodes_.SPACE ||
            evt.keyCode === this.Keycodes_.ENTER) {
        evt.preventDefault();
        // Send mousedown and mouseup to trigger ripple.
        var e = new MouseEvent('mousedown');
        evt.target.dispatchEvent(e);
        e = new MouseEvent('mouseup');
        evt.target.dispatchEvent(e);
        // Send click.
        evt.target.click();
      } else if (evt.keyCode === this.Keycodes_.ESCAPE) {
        evt.preventDefault();
        this.hide();
      }
    }
  }
};

/**
 * Handles a click event on an item.
 * @private
 */
MaterialMenu.prototype.handleItemClick_ = function(evt) {
  'use strict';

  if (evt.target.getAttribute('disabled') !== null) {
    evt.stopPropagation();
  } else {
    // Wait some time before closing menu, so the user can see the ripple.
    this.closing_ = true;
    window.setTimeout(function(evt) {
      this.hide();
      this.closing_ = false;
    }.bind(this), this.Constant_.CLOSE_TIMEOUT);
  }
};

/**
 * Calculates the initial clip (for opening the menu) or final clip (for closing
 * it), and applies it. This allows us to animate from or to the correct point,
 * that is, the point it's aligned to in the "for" element.
 * @private
 */
MaterialMenu.prototype.applyClip_ = function(height, width) {
  'use strict';

  if (this.element_.classList.contains(this.CssClasses_.UNALIGNED)) {
    // Do not clip.
    this.element_.style.clip = null;
  } else if (this.element_.classList.contains(this.CssClasses_.BOTTOM_RIGHT)) {
    // Clip to the top right corner of the menu.
    this.element_.style.clip =
        'rect(0 ' + width + 'px ' + '0 ' + width + 'px)';
  } else if (this.element_.classList.contains(this.CssClasses_.TOP_LEFT)) {
    // Clip to the bottom left corner of the menu.
    this.element_.style.clip =
        'rect(' + height + 'px 0 ' + height + 'px 0)';
  } else if (this.element_.classList.contains(this.CssClasses_.TOP_RIGHT)) {
    // Clip to the bottom right corner of the menu.
    this.element_.style.clip = 'rect(' + height + 'px ' + width + 'px ' +
        height + 'px ' + width + 'px)';
  } else {
    // Default: do not clip (same as clipping to the top left corner).
    this.element_.style.clip = null;
  }
};

/**
 * Adds an event listener to clean up after the animation ends.
 * @private
 */
MaterialMenu.prototype.addAnimationEndListener_ = function() {
  'use strict';

  var cleanup = function () {
    this.element_.removeEventListener('transitionend', cleanup);
    this.element_.removeEventListener('webkitTransitionEnd', cleanup);
    this.element_.classList.remove(this.CssClasses_.IS_ANIMATING);
  }.bind(this);

  // Remove animation class once the transition is done.
  this.element_.addEventListener('transitionend', cleanup);
  this.element_.addEventListener('webkitTransitionEnd', cleanup);
};

/**
 * Displays the menu.
 * @public
 */
MaterialMenu.prototype.show = function(evt) {
  'use strict';

  if (this.element_ && this.container_ && this.outline_) {
    // Measure the inner element.
    var height = this.element_.getBoundingClientRect().height;
    var width = this.element_.getBoundingClientRect().width;

    // Apply the inner element's size to the container and outline.
    this.container_.style.width = width + 'px';
    this.container_.style.height = height + 'px';
    this.outline_.style.width = width + 'px';
    this.outline_.style.height = height + 'px';

    var transitionDuration = this.Constant_.TRANSITION_DURATION_SECONDS *
        this.Constant_.TRANSITION_DURATION_FRACTION;

    // Calculate transition delays for individual menu items, so that they fade
    // in one at a time.
    var items = this.element_.querySelectorAll('.' + this.CssClasses_.ITEM);
    for (var i = 0; i < items.length; i++) {
      var itemDelay = null;
      if (this.element_.classList.contains(this.CssClasses_.TOP_LEFT) ||
          this.element_.classList.contains(this.CssClasses_.TOP_RIGHT)) {
        itemDelay = ((height - items[i].offsetTop - items[i].offsetHeight) /
            height * transitionDuration) + 's';
      } else {
        itemDelay = (items[i].offsetTop / height * transitionDuration) + 's';
      }
      items[i].style.transitionDelay = itemDelay;
    }

    // Apply the initial clip to the text before we start animating.
    this.applyClip_(height, width);

    // Wait for the next frame, turn on animation, and apply the final clip.
    // Also make it visible. This triggers the transitions.
    window.requestAnimationFrame(function() {
      this.element_.classList.add(this.CssClasses_.IS_ANIMATING);
      this.element_.style.clip = 'rect(0 ' + width + 'px ' + height + 'px 0)';
      this.container_.classList.add(this.CssClasses_.IS_VISIBLE);
    }.bind(this));

    // Clean up after the animation is complete.
    this.addAnimationEndListener_();

    // Add a click listener to the document, to close the menu.
    var callback = function(e) {
      // Check to see if the document is processing the same event that
      // displayed the menu in the first place. If so, do nothing.
      // Also check to see if the menu is in the process of closing itself, and
      // do nothing in that case.
      if (e !== evt && !this.closing_) {
        document.removeEventListener('click', callback);
        this.hide();
      }
    }.bind(this);
    document.addEventListener('click', callback);
  }
};

/**
 * Hides the menu.
 * @public
 */
MaterialMenu.prototype.hide = function() {
  'use strict';

  if (this.element_ && this.container_ && this.outline_) {
    var items = this.element_.querySelectorAll('.' + this.CssClasses_.ITEM);

    // Remove all transition delays; menu items fade out concurrently.
    for (var i = 0; i < items.length; i++) {
      items[i].style.transitionDelay = null;
    }

    // Measure the inner element.
    var height = this.element_.getBoundingClientRect().height;
    var width = this.element_.getBoundingClientRect().width;

    // Turn on animation, and apply the final clip. Also make invisible.
    // This triggers the transitions.
    this.element_.classList.add(this.CssClasses_.IS_ANIMATING);
    this.applyClip_(height, width);
    this.container_.classList.remove(this.CssClasses_.IS_VISIBLE);

    // Clean up after the animation is complete.
    this.addAnimationEndListener_();
  }
};

/**
 * Displays or hides the menu, depending on current state.
 * @public
 */
MaterialMenu.prototype.toggle = function(evt) {
  'use strict';

  if (this.container_.classList.contains(this.CssClasses_.IS_VISIBLE)) {
    this.hide();
  } else {
    this.show(evt);
  }
};

// The component registers itself. It can assume componentHandler is available
// in the global scope.
componentHandler.register({
  constructor: MaterialMenu,
  classAsString: 'MaterialMenu',
  cssClass: 'mdl-js-menu'
});